The invention relates to an apparatus and method for checking the operating condition of a fluid flow and pressure control member such as an injector, a valve, a flap, a safety unit etc., hereinafter called a such "control member".
It is known that control members must ensure the flow of the fluid as soon as the latter has reached a certain so-called calibration pressure, but also they must completely interrupt the flow when the pressure of the fluid is lower than the appointed calibration pressure and ensure at least a predetermined flow of this fluid as soon as its pressure exceeds the calibration pressure.
It is hitherto known to use for checking the operation of such control members an installation comprising a pump which removes fluid from a tank and delivers it to a circuit which passes through a flowmeter and to the control member before returning to the tank.
Between the flowmeter and the control member is connected on the one hand a pressure reader in the said circuit and on the other hand a direct return pipe to the tank under the control of a manual valve.
In this installation the method of checking is very old-fashioned. For instance, to check the calibration pressure the manual valve must gradually be closed in order to reduce the delivery through a by-pass pipe which increases the pressure in the main pipe until there is some flow from the control member.
The pressure in the circuit is then checked and if it does not correspond to the desired pressure the control member is regulated; then this process is repeated and the pressure rechecked until the correct pressure is reached by successive trials.
In order to check the fluid-tightness of the control member, which fluid tightness must be total as soon as the fluid therein is at a reference pressure which is lower than the calibration pressure, the manual valve is operated until the said reference pressure is obtained in the circuit and the control member is inspected immediately to ensure that there is no longer a flow.
In order to check that a certain desired flow is obtained as soon as the pressure of the fluid arriving at the control member is at another reference pressure which is greater than the calibration pressure, the manual valve is again operated until the aforesaid greater reference pressure is obtained in the circuit and a reading is immediately taken from the flowmeter, taking into account the possible effect on the flowmeter, according to its connection point, of the flow through the by-pass of the control member. It is evident that this by-pass cannot be interrupted because this would further increase pressure in the circuit.